1. Field of the Invention
The present invention relates to a method and an apparatus for terminal connections, and more particularly, to a method and an apparatus for separated uplink and downlink terminal connections.
2. Description of the Related Art
In a heterogeneous cellular network, a difference in transmission power and antenna gain may occur among base stations. In a case of connecting to a base station based on the transmission power of one of a downlink and an uplink, a loss in a signal to interference noise ratio (SINR) may be incurred on the other due to the difference. Thus, an issue of SINR unfairness may arise in the downlink and the uplink.
In general, a transmission power of a macrocell base station may be relatively greater than a transmission power of a femtocell base station. Thus, in the heterogeneous cellular network, a difference in coverage areas of the base stations may occur due to the difference in the transmission power and the antenna gain among the base stations.
Coverage of the macrocell base station having a relatively greater transmission power may be larger than a coverage area of the femtocell base station. Accordingly, a greater number of terminals may connect to the macrocell base station, and a load balancing issue in terms of a disproportionate number of terminals being connected to each of the base stations may arise. To solve such an issue, a method of determining a new terminal connection may be required.
Coverage of a cell association based on a downlink signal may differ from coverage of a cell association based on an uplink. Thus, an optimal cell association based on the downlink may differ from an optimal cell association based on the uplink.
When a terminal performs a cell association with a single base station, the terminal may generally perform the cell association with the base station based on the downlink signal. Accordingly, the terminal may not perform a cell association with an optimal base station in terms of the uplink and thus, the loss in the SINR may occur and the issue of unfairness between an SINR of the downlink and an SINR of the uplink may arise.
Moreover, a protocol for the cell association based on the uplink may not be found in conventional standards and technologies. Therefore, a method of and a protocol for determining a separate cell association in relation to the uplink may be needed.